The Armour Save of a model part is determined by its armour and possibly also by special rules and spells.

There are 5 different types of Armour:
Suits of Armour, Shields, Mounts, Innate Defence, and Other.

The Armour Save of a model part is determined by its armour and possibly also by special rules and spells. Combine all the armour pieces a model has to form a combined Armour Save. Each piece of armour adds +1 (or more)to the Saving Throw, up to a maximum total of +6. If the Armour Saving Throw, including modifiers, equals 7 or more, the Saving
Throw is successful. An unmodified roll of '1' is always a failure.

For example, if a model has a Light Armour (+1), Shield (+1), Helm (+1) and is mounted on a steed with Mount’sProtection (6+) (+1) and with Barding (+1), it has a total of +5 to its Armour Saving Throws, meaning a score of 2+ will equal 7 or more (and thus being a successful Saving Throw). Normally such an Armour Save would be referred to as a2+ Armour Save. Note that with a total of +6 to Armour Save, no model can ever have a better save than 1+ (and even with this, an unmodified score of '1' will always be a failed Armour Saving Throw).